What reagent is specifically used in the direct HDL cholesterol method?

The direct HDL cholesterol method specifically utilizes sulfated cyclodextrin as a reagent. This compound plays a critical role in the selective separation of HDL cholesterol from other lipoproteins in the sample. By forming a complex with other lipoproteins, sulfated cyclodextrin allows for the accurate measurement of HDL cholesterol levels without the need for prior precipitation methods that can be cumbersome and time-consuming.

In this context, the function of sulfated cyclodextrin exemplifies its utility in enhancing specificity and sensitivity in lipid assays. By promoting the solubilization of HDL, the reagent ensures that the subsequent enzymatic reactions can effectively target only the HDL fraction, leading to more reliable and reproducible results in laboratory analysis.